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Oracle中查询某个表的总字段数，要用SQL语句，或者在PL/SQL里面 复制代码 代码如下: select count(column_name) from user_tab_columns where table_name='T_B_AUDITOR' 能够查出来指定的那张表的字段数。 下面是通过大致查看： select tname,count(*) from col group by tname; 复制代码 代码如下: 64 T_A_BOOKSTAGEINFO 4 65 T_B_AUDITOR 14 66 T_B_BOOKMANAGEMENT 13 67 T_B_BOOKSTATUSCONFIG 5 68 T_B_CODETREEINFO 8 69 T_B_FILTERWORD 11 70 T_B_ISBNWHITELIST 11 71 T_B_MODEL 10 72 T_B_NOTICE 15 73 T_B_NOTICEACCEPT 11 74 T_B_OPERLOG 10 75 T_B_ORGANIZATIONINFO 18 76 T_B_PREFIXINFO 15 77 T_B_PUBLISHINFO 30 78 T_B_ROLE 8 79 T_B_ROLEMODEL 6 80 T_B_SAMPLEBOOKINFO 89 81 T_B_USER 26 82 T_B_USERANDROLE 6 83 T_B_USERLOGIN 8 84 T_B_USERMODEL 6 此时我就联想到了mysql上面去： 直接利用函数来解决： 复制代码 代码如下: mysql> desc test; +---------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------+-------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(10) | YES | | NULL | | | address | varchar(30) | YES | | NULL | | +---------+-------------+------+-----+---------+----------------+ 3 rows in set (0.01 sec) mysql> select found_rows(); +--------------+ | found_rows() | +--------------+ | 3 | +--------------+ 1 row in set (0.01 sec) 还有就是利用系统表： 复制代码 代码如下: mysql> use information_schema Database changed mysql> select count(*) from columns where table_name="test"; +----------+ | count(*) | +----------+ | 3 | +----------+ 1 row in set (0.00 sec) 在mysql中想要知道数据库中有多少个库： 复制代码 代码如下: mysql> select * from schemata; +--------------+--------------------+----------------------------+------------------------+----------+ | CATALOG_NAME | SCHEMA_NAME | DEFAULT_CHARACTER_SET_NAME | DEFAULT_COLLATION_NAME | SQL_PATH | +--------------+--------------------+----------------------------+------------------------+----------+ | NULL | information_schema | utf8 | utf8_general_ci | NULL | | NULL | mysql | utf8 | utf8_general_ci | NULL | | NULL | test | utf8 | utf8_general_ci | NULL | +--------------+--------------------+----------------------------+------------------------+----------+ 3 rows in set (0.00 sec) 在mysql数据库中有多少张表： 复制代码 代码如下: mysql> select table_schema,count(*) from tables group by table_schema; +--------------------+----------+ | table_schema | count(*) | +--------------------+----------+ | information_schema | 17 | | mysql | 17 | | test | 6 | +--------------------+----------+ 3 rows in set (0.00 sec) 其实在系统表information_schema中大多的数据库，表啊都会有记录的。所以要好好研究下这张表呢。 |
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